Gallium nitride-based devices (e.g., light emitting diodes (LEDs), transistors, etc.) are typically fabricated on foreign substrates such as sapphire, Si, etc. due to the relatively moderate costs for large-sized wafers. However, the large mismatch of the lattice constants and thermal expansion coefficients between foreign substrates and epitaxial layers lead to generation of a large number of extended defects and consequently inferior device performance. In recent years, significant progress has been made in the fabrication of GaN substrates. The higher priced substrates are typically used for devices that are operated under high power densities (e.g., laser diodes or high power LEDs). While these substrates offer a number of advantages (lower defect densities, shorter growth time, simpler processing steps) it seems unlikely that substrate costs for high-quality, large-area GaN wafers will drop sufficiently for large-scale manufacturing in the foreseeable future.